Magnetic stirring bars are useful in clinics, medical laboratories, research laboratories, and other similar facilities wherein it is necessary to stir solutions or specimens. Such magnetic stirring bars generally include a permanent magnet designed such that the magnetic pole axis is oriented substantially horizontally across the bar. The bar is typically positioned in a beaker, flask, or other similar containers containing a solution or specimen to be stirred. The container is typically placed on a conventional magnetic stirrer which provides a magnetic field for rotating the stirring bar and to stir the solution or specimen.
When liquid to be stirred is situated in a container with gels and other similar sensitive substances, conventional prior art stirring bar devices are often too harsh for sensitive gel structures. For example, it is not uncommon for the magnetic stirring bar positioned in a solution above a gel to bore a hole or break apart the gel into small fragments, when it is spun by a magnetic field. Thus, the sensitive nature of the gel structure can be seriously damaged or destroyed through the violent rotation of the magnetic stirring bar. This makes the use of such prior art stirring devices to be undesirable, especially when the integrity of the gels or other chemical or biological sample must be maintained.
Furthermore, applying an external rotating magnetic field to create free rotation of the magnetic stirring device causes mixing or stirring action of the entire volume of the solution, liquid, or other fluid surrounding the stirring bar. The efficiency of the stirring action is sometimes compromised in view of the uncontrolled flow and broad nature of the stirring magnet operation. Use of such conventional prior art devices is not always desirable, especially when the stirring action should be directed to a substantially limited area or region of a chemical or biological sample.
It has been therefore a long felt and unsolved need for a magnetic stirring arrangement capable of providing a gentle stirring action which does substantially effect the integrity of the substances exposed to the stirring process. There is also a need for a stirring device or arrangement capable of providing a stirring action directed to a substantially limited area or region of the solution or liquid, a device which is simple in use, inexpensive to manufacture, and can be easily cleaned and/or sterilized, so as to avoid undesirable contamination.